U.S. patent number 4,955,683 [Application Number 07/339,799] was granted by the patent office on 1990-09-11 for apparatus and a method for coupling an optically operative device with an optical fiber.
This patent grant is currently assigned to Sumitomo Electric Industries, Ltd.. Invention is credited to Keigo Aga, Takeshi Sekiguchi, Nobuo Shiga.
United States Patent |
4,955,683 |
Shiga , et al. |
September 11, 1990 |
Apparatus and a method for coupling an optically operative device
with an optical fiber
Abstract
This invention relates to an optical module for coupling an
optically operative device with an optical fiber. Near the
optically operative device, the module includes a fiber saddle on
which the optical fiber is affixed by soldering to optically
connect the operative device and the fiber. The fiber saddle is
provided on a heat insulative substrate, which also mounts the
optically operative device, so that heat for melting the solder
will not be conducted through the fiber saddle when the optical
fiber is soldered to the saddle. Thus, the temperature necessary
for soldering can be attained rapidly. A mounting surface of the
fiber saddle is plated with solder. A pre-formed solder structure
is bridged over the optical fiber after it is positioned on the
fixation surface. The pre-formed structure is melted and then
allowed to solidify whereby the optical fiber is affixed to the
fiber saddle to prevent dislocation of the fiber. The optically
operative device is kept free of contamination by flux during
soldering of the optical fiber.
Inventors: |
Shiga; Nobuo (Kanagawa,
JP), Sekiguchi; Takeshi (Kanagawa, JP),
Aga; Keigo (Kanagawa, JP) |
Assignee: |
Sumitomo Electric Industries,
Ltd. (Osaka, JP)
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Family
ID: |
26441867 |
Appl.
No.: |
07/339,799 |
Filed: |
April 18, 1989 |
Foreign Application Priority Data
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Apr 22, 1988 [JP] |
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63-100927 |
Apr 22, 1988 [JP] |
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63-100928 |
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Current U.S.
Class: |
385/88; 250/552;
385/15 |
Current CPC
Class: |
G02B
6/4202 (20130101); G02B 6/4238 (20130101); G02B
6/4248 (20130101) |
Current International
Class: |
G02B
6/42 (20060101); G02B 006/36 () |
Field of
Search: |
;350/96.18,96.15,96.17,96.20 ;250/227,552 ;357/17,19,30,74,80 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2503458 |
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Oct 1982 |
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FR |
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53-128991 |
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Nov 1978 |
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JP |
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61-73206 |
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Apr 1986 |
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JP |
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61-173205 |
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Apr 1986 |
|
JP |
|
Primary Examiner: Sikes; William L.
Assistant Examiner: Heartney; Phan T.
Attorney, Agent or Firm: Beveridge, DeGrandi &
Weilacher
Claims
We claim:
1. An apparatus for coupling an optically operative device with an
optical fiber, said apparatus comprising:
a ceramic board;
a saddle affixed on the surface of said ceramic board for
supporting an optical fiber thereon;
an optically operative device mounted on said ceramic board on
which said saddle is mounted; and
a metal package for housing said ceramic board.
2. An apparatus according to claim 1, wherein said optically
operative device comprises a light receiving device.
3. An apparatus according to claim 1, wherein said optically
operative device comprises a light emitting device.
4. An apparatus according to claim 1, wherein said saddle is formed
of a ceramic material and the surfaces of said saddle are
metallized by evaporated metal.
5. An apparatus according to claim 1, wherein said saddle has a
cavity therein and wherein said apparatus further comprises a
bridge-shaped solder structure having a leg adapted for insertion
into said cavity.
6. A method of fabricating a device for coupling an optically
operative device with an optical fiber, said method comprising the
steps of:
affixing a saddle and an optically operative device on a single
ceramic board;
disposing said ceramic board in a metal package;
inserting a leading edge of an optical fiber through an opening
provided in said metal package into said metal package;
positioning said optical fiber on said saddle in optical connection
with said optically operative device; and,
affixing said optical fiber on said saddle by soldering.
7. A method according to claim 6, wherein optically a light
receiving device is provided as said operative device.
8. A method according to claim 6, wherein a light emitting device
is provided as said optically operative device.
9. A method according to claim 6, wherein saddle is formed of a
ceramic material and the surfaces of said saddle are metallized by
evaporated metal.
10. A method of fabricating a device for coupling an optically
operative device with an optical fiber, said method comprising the
steps of:
affixing a saddle and an optically operative device on a single
ceramic board;
disposing said ceramic board in a metal package;
inserting a leading edge of an optical fiber through an opening
provided in said metal package into said metal package;
placing a solder block having a bridge-like shape on said saddle so
that said solder block bridges over said optical fiber; and,
positioning said optical fiber into optical connection with said
optically operative device and melting said solder block to affix
said optical fiber on said saddle.
11. A method according to claim 10, wherein a light receiving
device is provided as said optically operative device.
12. A method according to claim 10, wherein a light emitting device
is provided as said optically operative device.
13. A method according to claim 10, wherein said solder block does
not contain flux.
14. A method according to claim 10, wherein said saddle has at
least one cavity therein, said method further comprising a step of
inserting a part of said solder block into said cavity.
15. A method of fabricating a device for coupling an optically
operative device with an optical fiber, said method comprising the
steps of:
affixing a saddle and an optically operative device on a single
ceramic board;
disposing said ceramic board in a metal package,
placing a solder block having a bridge-like shape on said
saddle,
inserting a leading edge of an optical fiber through an opening
provided in said metal package into said metal package so that said
solder block bridges over said optical fiber; and,
positioning said optical fiber in optical connection with said
optically operative device and thereafter melting said solder block
to affix said optical fiber on said saddle.
16. A method according to claim 15, wherein a light receiving
device is provided as said optically operative device.
17. A method according to claim 15, wherein a light emitting device
is provided as said optically operative device.
18. A method according to claim 15, wherein said solder block does
not contain flux.
19. A method according to claim 15, wherein said saddle has at
least one cavity therein, said method further comprising a step of
inserting a part of said solder block into said cavity.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical module for use in
optical communication systems, such as data links, optical local
area networks (LANs), etc , which use light as an information
transmitting medium.
2. Related Background Art
There has been known an optical module comprising an optically
operative device, such as semiconductor lasers, pin-photodiodes and
others, and optical fibers optically connected to each other in a
metal package.
In such an optical module, the end of an optical fiber inserted in
the metal package is soldered to a fiber saddle in the package, and
the fiber saddle is molded in one piece with the package. A problem
with such known structures is that when a change is made to the
shape or location of the fiber saddle, a new mold including that of
the package has to be prepared, and consequently, such structure
cannot be adjusted to changes.
Another problem is that since the fiber saddle and the package are
made of metal and made in one piece, the package acts as a heat
sink when the end of the optical fiber is soldered to the fiber
saddle. This is disadvantageous because it takes much energy and
time to melt a solder on the fiber saddle. Consequently the
workability is poor.
Further, another problem is that when the soldering is performed,
soldering flux evaporates and attaches to the light emitting
portion or receiving portion, smearing the same. Also, part of the
solder which has not melted due to insufficient heating can touch
the end of the optical fiber and dislocate it from its correct
position such that the end of the optical fiber is fixed in an
incorrect position.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide an optical
module having a large tolerance for changes in shapes and locations
of a fiber saddle for an optical fiber thereto be soldered to.
A second object of the present invention is to provide an optical
module having a structure which enables an optical fiber to be
soldered to a fiber saddle in a short period of time.
Accordingly, the present invention provides an optical module
having a fiber saddle secured to a substrate made of highly heat
insulative material.
A third object of the present invention is to provide an optical
module having an optically operative device which is free of
soldering flux contamination.
A fourth object of the present invention is to provide an optical
module having an optical fiber secured precisely at a position in
which the optical fiber has been positioned with respect to an
optically operative device.
Accordingly the present invention provides an optical module in
which a fixation surface of a fiber saddle to which an optical
fiber is to be secured, is plated with solder, a pre-formed
structure made of solder is bridged over the optical fiber
positioned on the fixation surface, and the pre-formed structure is
melted and then allowed to solidify, whereby the optical fiber is
secured to the fiber saddle.
The present invention will be more fully understood from the
following detailed description and the accompanying drawings which
are provided by way of illustration only, and thus are not to be
considered as limiting the scope of the present invention.
Further scope of the present invention will become apparent from
the following detailed description. However, it should be
understood that the detailed description and specific examples,
while indicating preferred embodiments of the invention, are given
by way of illustration only, since various changes and
modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings
FIG. 1, is a perspective view of a major part of the optical module
according to one embodiment of the present invention;
FIG. 2 is a partial perspective view of the embodiment of FIG. 1
for use in explaining fixation of an optical fiber;
FIG. 3 is a front view of the embodiment of FIG. 1; and
FIGS. 4 and 6 are front views of modified pre-formed structures
according to alternative embodiments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In an optical receiving module according to one embodiment of the
present invention, as shown in FIG. 1, in a metal package 3 there
is provided a hybrid integrated circuit (IC) or board 6 having a
required circuit not shown. Openings are formed in the side walls
of the package 3. Through the openings an electric signal line 8
and an optical fiber 1 are inserted in the package 3.
The optical fiber 1 is optically connected to a pin-photodiode (not
shown) provided on a side of a carrier chip 2, and light emitted
from the end of the optical fiber 1 is incident on the light
receiving portion of the which acts as a light receiving
device.
The optical fiber 1 has an end 1a made of the so called metallized
fiber which comprises exposed glass fiber and a plating applied
thereto. The end 1a of the optical fiber 1 is first positioned
precisely on a fiber saddle 5 disposed near the carrier chip 2 and
then soldered to the fiber saddle 5.
The hybrid IC substrate 6 is made of a heat insulative material,
e.g., ceramics or other materials. The carrier chip 2 is mounted on
the substrate or board 6 as one element of the circuit. The fiber
saddle 5 is made of metal or ceramics vacuum evaporated with metal
and is beforehand plated with a solder. The fiber saddle 5 is die
bonded to the substrate 6 with a solder having a relatively high
melting point, e.g., gold and tin (Au-Sn) solder having a melting
point of 280.degree. C.
After a cream solder is applied around the fiber saddle 5, the
fiber saddle 5 is mounted on the substrate 6 and then heated. It is
possible that the plating and die bonding of the fiber saddle 5 are
performed simultaneously.
Next, the affixation of the end 1a of the optical fiber 1 to the
fiber saddle 5 will be explained with reference to FIGS. 2 and
3.
The end 1a of the optical fiber 1 is positioned so as to be
optically connected to the pin-photodiode 9 on the front side wall
of the carrier chip 2. Cavities 5a are formed on the top of the
fiber saddle 5. In the cavities 5a are inserted the legs of a
pre-formed structure 7 bridged over the end 1a of the optical fiber
1 positioned on the top of the fiber saddle 5. The preformed
structure 7 is made of a solder containing no flux and is shaped as
a square bracket. It is preferable that the solder of the
pre-formed structure 7 have a lower melting point than that used to
die bond the fiber saddle 5. The end Ia of the optical fiber 1 is
plated beforehand into a metallized fiber so as to be convenient
for soldering.
The pre-formed structure 7 and the fiber saddle 5 as arranged in
the above described manner are heated. When the heating temperature
exceeds the melting point of the pre-formed structure 7, the
pre-formed structure 7 melts. Then the heating is stopped. The
melted preformed structure 7 cools and solidifies, and the end 1a
of the optical fiber 1 is fixed to the fiber saddle 5.
The end 1a of the optical fiber 1 may be positioned on top of the
fiber saddle 5 after the legs of the pre-formed structure 7 are
inserted into cavities 5a. Then, the end 1a of the optical fiber 1
is disposed in the gap between the pre-formed structure 7 and the
fiber saddle 5.
In this embodiment, the pre-formed structure 7 has a square bracket
shape before melting. Alternatively, it may have a U-shape or an
L-shape as shown in FIGS. 4 and 5.
Finally, a top cover (not shown) is attached to the package for
close sealing, and the optical module is completed.
In this embodiment, two legs of the pre-formed structure 7 are
inserted into cavities 5a respectively. Alternatively, the
pre-formed structure may have a J-shape in which the two legs have
different lengths, and only one of the two legs is inserted in the
cavity 5a. In this case, there may be only one cavity 5a. And the
fiber saddle may not have cavities. In this case the pre-formed
structure can be placed on the fixation surface to be bridged over
the optical fiber positioned on the fixation surface.
This embodiment is a receiving optical module comprising a
pin-photodiode serving as a light receiving device, and an optical
fiber optically connected to the light receiving device. However,
the optical module according to this invention can be configured as
a transmitting optical module by replacing the light receiving
device with a light emitting diode or a laser diode serving as a
light emitting device.
From the invention thus described, it will be obvious that the
invention may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *